Russia has expelled a journalist for the British newspaper "The Guardian." The authorities have given no explanation for their action, but the correspondent reported on U.S. diplomatic cables uncovered by WikiLeaks that had angered the government.

Luke Harding said he was returning from London on February 5 when he was stopped at a border guard checkpoint in Moscow's Sheremyetevo airport.

"Someone disappeared into a side room with my passport and emerged rather rapidly and said, 'For you the Russian Federation is now closed,'" he said.

Harding was placed in a detention cell, then escorted to the next plane back to London. The Russian authorities have given no reason for his expulsion.

Writing On WikiLeaks

He had been in London for two months, where he was writing about WikiLeaks cables that concerned Russia. One of the most publicized described the country as a "virtual mafia state."

"The Guardian" editor Alan Rusbridger criticized Harding's expulsion in a statement, saying, "This is clearly a very troubling development with serious implications for press freedom."

The British Foreign Office said it's seeking "clarity on this decision."

Harding has had a tense relationship with the Russian authorities since he first arrived four years ago, at the height of a diplomatic row between London and Moscow over the poisoning of former KGB officer Alexander Litvinenko.

But he said "things got a lot worse" last year after he made trips to the volatile Caucasus region, where he interviewed the father of a suicide bomber who attacked the Moscow metro last year.

He said the Russian Foreign Ministry called him in for a meeting last November.

"They informed me that my annual accreditation, without which you can’t be in Russia because you need it to get a visa, was not being renewed and I had to leave the country by the end of the year,” he said. “They came up with two pretexts for this."

'Grave' Arctic Crime

Harding said he was told he'd committed a "grave crime" by joining other journalists for a trip to the Russian Arctic with Greenpeace using a permit in the name of another "Guardian" correspondent.

He said he was also criticized for traveling to the Caucasus region of Ingushetia last April, when he was questioned there by local Federal Security Service officers.

"I said to them I understand, but this is going to be a scandal, are you sure you really want to go down this road? I'll complain to the British Embassy and government,” he said. “They seemed pretty indifferent to that, which made me think that whoever had signed off on this was rather senior."

But Harding said the authorities later reconsidered and issued him a six-month visa, valid until May, after he had appealed their initial decision.

Moscow regularly ejects foreign correspondents, often in reprisal for expulsions of alleged Russian spies abroad. Last year, the Kremlin expelled Czech television correspondent Josef Pazderka after Czech authorities ejected a Russian journalist believed to have engaged in espionage.

Russia expelled a British diplomat last December after Britain ejected a Russian diplomat from London for espionage.

But foreign journalists have also been thrown out for stories they produced. In 2005, the government expelled a correspondent for the U.S. television network ABC after it aired an interview with Chechen rebel leader Shamil Basayev.It's Worse For Russian Reporters

Russian reporters fare much worse; beatings and killings take place regularly and are rarely solved. Russia is regularly ranked among the most dangerous countries in the world for journalists.

Harding -- who co-wrote a book about the WikiLeaks cables published by "The Guardian" last week -- is now in London while his wife and two young children remain temporarily in Moscow.

He says he won’t contest his expulsion. "I know it's just not possible and there's no point in testing it."